<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>


<div id="countdown"></div>



<script language="javascript" type="text/javascript">
    var time = 12
    var contain = document.getElementById("countdown")
    contain.innerHTML = time.toString() + "秒钟后系统自动跳转到百度。"

    function updateTime() {
        time = time - 1
        if (time >= 0) {
            contain.innerHTML = time.toString() + "秒钟后系统自动跳转到百度。"
        } else {
            contain.innerHTML = "正在跳转到关于我，请稍后。。。"
        }
    }

    setInterval("updateTime()", 1000);
    setTimeout("javascript:location.href='https://www.baidu.com/'", time * 1000);
</script>
</html>